Can LM check for Windows Updates?

I checked the Exchange and there looks to be a "_Windows patches needed" datasource that might be close to what you want. But in general what you are asking for sounds very doable but likely something you need to write code to implement. Using the PSWindowsUpdate powershell module might be useful for that.

One thing to keep in mind, in general you want datasources to run as fast as possible and they do have a timeout (2min by default in the collector). So you likely don't want to try to actually kick off a real windows update scans in the check unless you account for that.